The University of Minnesota is going to get a fresh look tomorrow at the upgrades the school’s stadium will need to host the Vikings for the 2014 and 2015 seasons.

The preliminary price tag on tomorrow’s agenda is $6.6 million in capital improvements, up from the $3.5 million that the team and school initially estimated in a 2013 agreeement. That’s when they reached a deal to host the NFL for at least 20 games while the Metrodome is being torn down and the new stadium is being built. Now, for the first time, the University and the Vikings have put together a solid estimate on what it’ll cost to upgrade “The Bank” for winter football.

The Vikings and the U say that original 2013 estimate did not include the price of a big ticket item: the final cost of upgrading the playing surface to keep the field at TCF Bank Stadium from freezing solid. The field will have to be heated for the Vikings. That’s a key element of the relocation project: quarterback Brett Farve blamed a concussion he suffered three seasons ago at least in part on the frozen field. It was the injury that helped end his football career in 2010.

Vikings spokesman Jeff Anderson said the added expense for the heating isn’t a surprise for the Vikings or the U. “When you have such a big ticket item included in the final number, you would expect that number to grow significantly. We always knew that number established in May was going to be higher because we had not gone through the building in the detail we have now.” The Vikings are paying the bill, which got preliminary approval from the Regents in June.

Here’s the budget from the original agreement between the Vikings and the University of Minnesota, dating to last May:

That said, the total cost of hosting the Vikings at TCF Bank stadium has actually declined. The Minnesota Sports Facilities Authority and the team initially budgeted $31 million for the move to the East Bank for two years, with $15 million of that to go to the Vikings to make up for revenue lost when the team moved to the smaller venue. The Vikings opted to shift that $15 million into their new stadium construction instead, in part to cover increased costs on that project.

The agreement has the Vikings paying $250,000 per game in rent, and up to $300,000 per game total, for a maxiumum of $3 million per NFL season. The Vikings are also contributing $125,000 in cash and in-kind contributions per season to the U’s “Good Neighbor Fund,” to help ease the Vikings move for the stadium’s neighbors.

Here’s the to do list the team and the U initially planned, as laid out in their May announcement:

Installation of new turf and an appropriate heating element for the playing surface to be determined by Vikings and University officials.

Potential installation of additional temporary seating in the western end zone plaza, subject to approval by the university’s building code division (number of seats yet to be determined by Vikings and University officials).